(a) Field of the Invention
The present invention relates to a device for driving a movable member such as, for example, a retractable head lamp or a wiper unit in a vehicle and, more particularly, to a device for driving a movable member, which is capable of manual operation for maintenance.
(b) Related Art Statement
As a device for driving a movable member necessary to move from a first position to a second position or vice versa such as a retractable head lamp or a wiper unit in a vehicle there is a type for decelerating the rotation of a motor in a predetermined direction through a reduction gear train, further converting the rotation into a reciprocating motion via a crank mechanism and then moving the head lamp body or the wiper blades of the wiper unit between the first position and the second position via a linkage.
However, in case of maintenance for example exchanging a lamp bulb, it is impossible to dispose the body of the head lamp or the wiper blades of the wiper unit to a desired position. To this end, a driving device which has manual operating means for disposing the head lamp at the desired position for maintenance has been proposed. The driving device of this type is disclosed, for example, in Japanese unexamined Utility Model Publication No. 57-170666 published on Oct. 27, 1982. In this driving device, a clutch plate is mounted on a rotational shaft of a motor at the side with which a load including a reduction gear train is not coupled, and a manual operating handle having the other clutch plate engaged in one direction with the clutch plate is provided. Since the manual rotational is transmitted to the shaft when rotating the manual operating handle in the operating direction of the motor by these clutch plates in this driving device, the shaft of the motor can be rotated by rotating the manual operating handle even when the motor is disabled, thereby driving the head lamp through the reduction gear train and the crank mechanism. However, in the driving device of this type, the shaft of the motor is manually rotated via a one-way clutch, and even if the manual operating handle is rotated rapidly, the head lamp to be driven is driven at a ratio of reciprocal of the reduction gear ratio by the reduction gear train. Thus, this driving device has a problem that driving of the head lamp by manual operation is not rapidly performed.